Automatic loading horizontal type of open-reel magnetic tape drive unit

ABSTRACT

A horizontal type of open-reel magnetic tape drive unit automatically clamps a tape reel in a drive section after the reel is inserted, then seperates the free end of the tape from the reel, and guides the free end of the tape along a tape transport path to be wound onto a take-up hub, with these separation and guidance operations being performed by a small number of high pressure air jets. Pressure sealing of the unit is unnecessary, and the overall configuration is simple and easily manufactured.

This is a division of application Ser. No. 573,896, filed Jan. 25, 1984,now U.S. Pat. No. 4,653,704.

BACKGROUND OF THE INVENTION

The present invention relates to a magnetic tape drive unit for use indata processing and computer applications, and in particular to alow-profile horizontal type of open-reel magnetic tape drive unit inwhich the magnetic tape is threaded from the tape reel to the take-uphub completely automatically, after the reel is inserted. The method ofautomatic threading is such that it is not necessary to hermeticallyseal the unit, and in fact such a magnetic tape drive unit can beoperated equally well with or without a cover, and so can be mounted inany of a variety of ways. For example, the unit can simply be placedhorizontally within a drawer.

There is a need at present for an automatic tape threading type ofmagnetic tape drive unit for use in data-processing and computerapplications which would have a simple mechanical configuration, forreduced manufacturing cost, and could be disposed horizontally (i.e.with the tape running along a substantially horizontal path) so that theunit has a low profile, suitable for rack mounting or drawer mounting.The need for an automatic threading capability is due to the fact thatmanual threading of the tape in such units will frequently result indamage to the tape, and moreover is extremely time-consuming for theoperator. Manural threading can of course be eliminated if the tape isdisposed within cassettes, such as are widely used for video recording.However this leads to a very considerable increase in the amount ofspace required for storing the tapes, and hence is highly undesirable.The need for a low profile is self-evident, since almost all of theother components of a data-processing installation are of an essentiallyflat, horizontal shape, and a vertical configuration is basicallyincompatible with drawer or rack mounted equipment. Various types ofautomatic-threading magnetic tape drive units are known in the priorart. However most of these are of a vertical configuration, which isundesirable for the reasons discussed above, and have a generallycomplex mechanism which is expensive to manufacture. The basic reasonfor the use of an upright configuration is that this enables the actionof gravity on the tape to be employed, to assist in guiding the tapealong a desired route in conjunction with other means such as air jets.

An automatic-threading magnetic tape drive unit having a horizontalconfiguration has been described by Peter et al (U.S. Pat. No.4,243,186). This utilizes suction, created at the take-up hub of theunit, to produce a current of air flowing from the exterior and along apath from the tape reel to the take-up hub. As stated in the Peter et alspecification, such a system utilizes an air flow having a high rate offlow at low pressure. With such a magnetic tape drive unit, it isnecessary to hermetically seal the unit by a cover, to ensure that theair flow is directed only along the desired path such as to transportthe free end of the tape to the take-up hub, when automatic threading ofthe tape is being performed In addition, due to the large rate of flowwhich is necessary, the equipment (i.e. blower fan, fan motor, etc) usedto produce the suction must be relatively large, so that the overallsize of the magnetic tape drive unit cannot be made extremely compactwith a very low profile. Furthermore, it is a basic disadvantage of suchan air suction type of magnetic tape drive unit that the air flow has noinherent effect tending to direct the free end of the tape along thecenter of the tape transport path (i.e. the vertical-walled channelwithin which the tape runs between the tape reel and the take-up hub).Thus it is found in practice with such a system that the free end of thetape tend to adhere to the walls of the tape transport path, of that thetape tends to become twisted, as it is being led towards the take-uphub, so that correct automatic threading operation cannot be reliablyattained. Moreover it is found that with such a system it is difficultto ensure that the free end of the tape will be reliably wound onto thetakeup hub, after it has been transported thereto by the air flow alongthe tape transport path, and the tape may be damaged when it is woundonto the take-up hub.

There is therefore a requirement for a horizontal type of open-reelmagnetic tape drive unit which will perform automatic threading of thetape from a reel along a predetermined path (having a magneticread/write head disposed at some point on that path) to a take-up hub,and automatic winding of the tape onto the take-up hub, in a reliableand accurate manner without damage to the tape or any need for manualintervention. It is also a requirement for such a magnetic tape driveunit that the overall configuration, preferably including means wherebya tape reel is automatically clamped onto a drive shaft when it isinserted into the unit, be simple and easily manufactured at low cost.Such requirements are not met by prior art types of magnetic tape driveunits.

SUMMARY OF THE INVENTION

It is an objective of the present invention to overcome the variousproblems which arise with prior art types of horizontal magnetic tapedrive units as described above, and to provide a low-profile horizontaltype of magnetic tape drive unit which will perform tape threading froma reel to a take-up hub, and winding of the tape onto the take-up hub,in a completely automatic manner.

A magnetic tape drive unit according to the present invention isessentially of the single-reel type, with the tape being wound from atape reel onto a take-up hub before read or write operations areperformed on the tape, and being rewound onto the tape reel after it hasbeen used. As described with reference to the preferred embodiments, thereel may be of the unenclosed type, or a cartridge may be used tocontain and protect the reel. With a magnetic tape drive unit accordingto the present invention, a tape reel which is loaded into a tape supplysection, i.e. by being inserted through a slot to fall into the tapesupply section or simply placed in the tape supply section, and the freeend of the tape wound on the tape reel is automatically separated fromthe adjacent tape (to which it tends to adhere) and pulled out to beguided and transported along the center of a tape transport path(comprising a channel of concave shape as viewed from above, disposedhorizontally connecting the tape supply section in which the tape reelis mounted and rotated to the tape take-up section containing thetake-up hub) to the tape take-up section by high-pressure air flows. Thefree end of the tape is then guided onto the peripheral face of therotating take-up hub and set in contact with that peripheral face bywinding securing means so as to become wound onto the take-up hub. Thus,after the tape reel has been inserted into the magnetic tape drive unit,threading of the tape from the tape reel onto the take-up hub of thetape take-up section is performed completely automatically, without anyhuman intervention being necessary. It is a basic feature of the presentinvention that all of the operations of separating the free end of thetape from the tape on the tape reel and guiding and transporting thefree end of the tape to the tape take-up section and onto the take-uphub are performed by high-pressure air flows, produced from a smallnumber (e.g. FIGS. 3 or 4) high-pressure air ejection outlets suppliedfrom high-pressure air supply means such as a blower fan. The operationof these high-pressure air flows is not affected by the state of sealingof the unit within a cover, so that the use of such a cover is purelyoptional. The high-pressure air flows act to guide the free end of thetape along the central region of the tape transport path, which can haveany desired curved shape, so that the free end of the tape does not comeinto contact with the side walls of the channel through which is moves.In this way, the problems of the tape adhering to the side walls orbecoming twisted, which arise with the prior art, are eliminated.

In addition, with a magnetic tape drive unit according to the presentinvention, the tape reel is automatically clamped onto a drive motorshaft in the tape supply section after manual insertion into the tapesupply section, and is automatically unclamped when the tape has beenrewound after use and is to be removed. The means for implementing thisclamping and unclamping of the tape reel are extremely simplemechanically by comparison with prior art means for performing such tapereel clamping, although highly effective, and can be manufactured at lowcost.

It is another important feature of a magnetic tape drive unit accordingto the present invention that means are provided for automaticallyseparating the free end of the tape from adjacent portions of the tapewound on the tape reel, before the free end of the tape is led to thetape take-up section. Due to the nature of magnetic tape, whichgenerally comprises a smooth plastic base, the free end of the tape willnaturally tend to adhere to adjacent portions of the tape. This cancause problems with prior art types of unit, in which no specific meansare provided for separating the free end of the tape. With a magnetictape drive unit according to the present invention, such separation ofthe free end of the tape is performed in a simple and effective mannerby a high-pressure air flow, in combination with rotation of the reel inan appropriate direction.

As a result of utilizing high-pressure air flows to guide and transportthe free end of the tape onto the take-up hub, it is not necessary toseal a magnetic tape drive unit according to the present inventionagainst the atmosphere, and in fact such a unit can be operated withouta cover if desired. It will of course be generally desirable to utilizesome form of cover or container to prevent the entry of dust etc intothe interior of the mechanism. However the elimination of the need forhermetic sealing of the magnetic tape drive unit represents asignificant advantage of the present invention over a magnetic tapedrive unit which employes a vacuum suction system to perform automatictape threading.

A magnetic tape drive unit according to the present invention basicallycomprises the following. A base is fixed horizontally within a housing,and a tape supply section is disposed in the base. The tape supplysection is provided with means for automatically clamping a tape reelonto a drive shaft, e.g. the shaft of a drive motor, with the rotationof the drive shaft and hence the tape reel being controlled by controlsignals from a control section. A tape take-up section is also providedon the base, and includes a take-up hub driven by a motor in response tocontrol signals, for winding the tape from the tape supply section. Atape transport path comprising an elongated open channel is formed inthe base, between the tape supply section and the tape take-up section,along which the tape runs after it has been wound onto the take-up hub.A head section disposed in the tape transport path between the tapesupply section and the tape take-up section includes magnetic head meansfor performing read and write operations on the moving tape. A pluralityof high-pressure air flows are produced by high-pressure air ejectionoutlets, supplied from means such as a blower fan, with thesehigh-pressure air flows being disposed such as to act to separate thefree end of the tape from adjacent portions of the tape on the tapereel, to guide and transport the free end of the tape after separation,along the central region of the tape transport path towards the tapetake-up section, and guiding and transporting the free end of the tapeonto the take-up hub in the tape take-up section. Winding securingmeans, such as an air flow guide surface acting to direct a flow of airtowards the take-up hub periphery operating in conjunction with a rollerbearing against the periphery of the take-up hub, act to wind the freeend of the tape onto the rotating take-up hub after it has ben guidedand transported thereto. The latter winding securing means can also bearranged such as to ensure evenness of winding the tape onto the take-uphub. A tape start/end detection section serves to detect passage of theleading end and the trailing end of the tape, and produce detectionsignals to indicate such passage. A tension application mechanism actsto produce a predetermined amount of tension in the tape after it hasbeen wound onto the take-up hub. Tape securing confirmation means serveto produce signals indicating that the tape has become securely woundonto the take-up hub. A tape control section comprises electroniccircuits which receives various detection signals from various sections,and produces control signals which control the operation of the motorsdriving the tape reel and the take-up hub.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a first embodiment of a magnetic tape driveunit according to the present invention, for use with cartride-enclosedtape reels;

FIG. 2 is a cross-sectional view of a tape drive section in theembodiment of FIG. 1;

FIG. 3 and FIG. 4 are diagrams for describing tape free end separationmeans in the embodiment of FIG. 1;

FIG. 5 is an expanded view in plan of a portion of the embodiment ofFIG. 1, for describing a tape end/start detection section;

FIG. 6 is a cross-sectional view of the tape end/start detection sectionof FIG. 5;

FIG. 7 and FIG. 8 are diagrams for describing another example of a tapeend/start detection section;

FIG. 9 is a simplified cross-sectional view of a tape take-up section inthe embodiment of FIG. 1;

FIG. 10 to FIG. 13 are diagrams for describing a tape tensionapplication mechanism used in the embodiment of FIG. 1;

FIG. 14 is a simplified block diagram of means for controlling theoverall operation of the embodiment of FIG. 1;

FIG. 15 is a plan view of an embodiment of a magnetic tape drive unitaccording to the present invention, for use with open tape reels;

FIG. 16 is a plan view of another embodiment of a magnetic tape driveunit according to the present invention, of open-reel type, having amodified form of tape supply section and tape tension applicationmechanism;

FIG. 17 is a cross-sectional view of a tape supply section in theembodiment of FIG. 16;

FIG. 18 is a plan view of a tape clamping mechanism in the embodiment ofFIG. 16, illustrating the condition thereof prior to a tape clampingoperation;

FIG. 19 is a cross-sectional view of the tape clamping mechanismcorresponding to the condition shown in FIG. 18;

FIG. 20 is a plan view illustrating the operation of a cam mechanism inthe clamping mechanism, prior to a reel clamping operation;

FIG. 21 is a plan view of the tape clamping mechanism, illustrating thecondition with a tape reel in the clamped status;

FIG. 22 is a cross-sectional view of the tape clamping mechanism,illustrating the condition thereof after a tape reel clamping operation,prior to retraction of a solenoid rod;

FIG. 23 is a plan view of the cam mechanism, corresponding to thecondition shown in FIG. 21 and 22;

FIG. 24 is a cross-sectional view for illustrating a micro-switchactuation mechanism in a tape tension application mechanism of theembodiment of FIG. 16;

FIG. 25 and FIG. 26 are partial views in plan and cross-section forillustrating the tension application mechanism in the embodiment of FIG.16; and

FIGS. 27a to 27d are partial views in plan to illustrate variousconditions of a tension arm in the tension application mechanism of FIG.16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of a magnetic tape drive unit according to the presentinvention, and various mechanisms used therein, will now be describedwith reference to the drawings. FIG. 1 is a plan view of a firstembodiment of a magnetic tape drive unit according to the presentinvention. Numeral 12 denotes a base which is fixedly attached within ahousing 10. Housing 10 is designed to be mounted horizontally, with base12 also being disposed horizontally.

Numeral 14 denotes a tape supply section, and numeral 16 denotes a tapetake-up section, each formed in a concave shape (as viewed from above)at opposite ends of base 12. Numeral 18 denotes a tape transport path,comprising an open channel formed in base 12 (i.e. having a concaveshape as viewed from above), having an identical depth to the tapesupply section and tape take-up sections, and which is curved into anS-shaped path connecting the tape supply section 14 and tape take-upsection 16.

Numeral 20 denotes a tension application mechanism, which acts to applya predetermined degree of tension to a magnetic tape (hereinafter simplyreferred to as "tape") 22 after the tape has been wound onto a take-uphub as described hereinafter. Numeral 24 denotes a tape start/enddetection section, which acts to detect the start and the end of tape22. Numeral 26 denotes a magnetic read/write head, for performing readand write operations on tape 22, and numeral 28 denotes a cleaner forcleaning tape 22. As shown, tension application mechanism 20, tapestart/end detection section 24, magnetic head 26 and cleaner 28 are alldisposed at intermediate points along tape transport path 18. Numerals30, 32, 34 and 38 denote high-pressure air ejection outlets which serveto produce high-pressure air flows, whose functions are described indetail hereinafter. These high-pressure air flows are generated by anair supply applied through a supply outlet 36 from a high-pressure airsupply source 40, which can comprise means such as a blower fanconnected by pipes or ducts to high-pressure air supply outlet 36, theair supply then passing from supply outlet 36 through the interior ofbase 12, to be output from high-pressure air ejection outlets 30, 32, 34and 38.

Numeral 42 denotes the reel on which the tape is wound. For ease ofdescription, the portion of tape following the free end of the tapeafter separation from the coil of tape wound on the reel will bedesignated by reference numeral 22, while the tape which is still woundon reel 42 will be designated by numeral 44. In this embodiment, thereel 42 is enclosed within a cartridge 46, to protect the tape when itis removed from the unit.

Basically, air ejection outlets 30 and 32 act to produce air currentswhich serve in conjunction with rotation of reel 42 in an appropriatedirection to separate the free end of the tape from adjacent portions ofthe tape 44, immediately after the cartridge is inserted into tapesupply section 14, The high-pressure air flow produced by high-pressureair ejection outlet 34 acts, in conjunction with the air flows producedby air ejection outlets 30 and 32, to pull the free end of the tape intothe tape transport path 18, and to guide and transport the free end ofthe tape along the center of tape transport path 18 towards tape take-upsection 16. The air flow produced by high-pressure air ejection outlet38 is directed such as to modify the direction of advancement of thefree end of the tape as it moves towards the tape take-up section, aswell as to transport the free end of the tape towards the tape take-upsection, so that the tape follows the curvature of the tape transportpath 18, and continues to move substantially along the center of thatpath. Numeral 48 denotes a winding securing mechanism, which serves toguide the free end of the tape into contact with the peripheral surfaceof a take-up hub 49 in the tape take-up section. At that time, thetake-up hub 49 is rotating, and winding securing mechanism 48 functionssuch as to cause tape 22 to become wound onto take-up hub 49, asdescribed hereinafter. In this embodiment, the winding securingmechanism 48 also constitutes means for applying pressure to tape 22after it has been wound onto take-up hub 49, so as to preventnon-uniformity of winding of the tape on take-up hub 49.

The tape supply section 14 will now be described with reference to FIGS.2 to 4. FIG. 2 is a vertical cross-sectional view of tape supply section14, and illustrates the condition of tape supply section 14 immediatelyafter a cartridge 46 has been inserted into the magnetic tape driveunit, before the reel is clamped in place. Numeral 50 denotes a drivemotor and numeral 51 the drive shaft of motor 50.

The cartridge support section 52 is disposed around the periphery of thelower face of cartridge 46, on top of the convex base section 54 of tapesupply section 14. A shield member 56 is disposed between the upper endof drive motor 50 and the convex base portion 54, and acts to shield thespace between drive motor 50 and the base. In addition, a high-pressureair ejection outlet 30 is disposed at one end of shield member 56. Thus,the high-pressure air flow which is ejected from air ejection outlet 30flows through the air gap 60, and through the space between cam 109 andconvex base portion 54, enters space 62 formed between reel 42 and baseportion 54, and furthermore flows from the gap at the lower end of reel42 into the interior of cartridge 46. The air flow which passes intocartridge 46 flows towards and out through tape leadout aperture 64.

FIG. 3 is a diagram for describing the way in which the free end of thetape is drawn out of cartridge 46. The dark arrows shown in FIG. 3indicate the direction of movement of the air flow, while the lengths ofthe arrows indicate the strength of the air flow. Cartridge 46 has anouter peripheral wall which is formed into a hollow shell configurationi.e. a space is formed between vertical peripheral walls of cartridge46. In addition to tape leadout aperture 64 provided in cartridge 46, anair entry aperture section 46a is provided with a plurality of smallthrough-hole apertures 68, formed in the outer vertical wall ofcartridge 46 as shown in FIG. 4. This air entry aperture section 46a ispositioned immediately opposite and adjacent to the high-pressure airejection outlet 32, formed in the right-hand side of tape supply section14. Thus, the high-pressure air flow from high-pressure air ejectionoutlet 32 flows through the apertures 68 into the interior of the spaceformed between the vertical peripheral walls of cartridge 46. A numberof small through-hole apertures are formed in the inner peripheralvertical wall of cartridge 46, and the air from high-pressure airejection outlet 32 thereby flows through these inner apertures into theinterior of cartridge 46. The air which is ejected from these innerapertures, in directions indicated by the white arrows in FIG. 3, isdirected onto tape 44 in such a way as to separate the free end of tape44 wound on reel 42 from adjacent portions of the tape (to which thefree end of the tape naturally tends to adhere, due to the form of suchmagnetic tape).

At the same time, reel 42 is rotated by motor 50, in the clockwisedirection as viewed from above (i.e. in a direction such as to assistseparation fo the free end of the tape from the adjacent tape portions).As a result of this rotation and the inwardly directed air flowsdescribed above, the free end of the tape is reliably separated from theadjacent tape portions.

The air flow resulting from the output of high-pressure air ejectionoutlet 30 has a distribution illustrated by the black arrows in FIG. 3.Due to the strength of the air flow which enters the interior ofcartridge 46 from air ejection outlet 30, there is an increase in theair pressure within cartridge 46 above the atmospheric pressure exteriorto tape leadout aperture 64. As a result of this pressure difference,the free end of the tape is pulled out through tape lead-out aperture64. The free end of the tape is thereby reliably transported out ofcartridge 46, by the air flowing out of cartridge 46 through tapeleadout aperture 64. There is no danger that the free end of the tapewill drop into the angular space between the lower side of reel 42 andcartridge 46, since this is prevented by the flow of air into theinterior of cartridge 46 through the annular aperture formed between thelower side of reel 42 and cartridge 46, as described hereinabove.

More specifically, after the free end of the tape has been separatedfrom the adjacent tape it is led along the internal vertical wall faceof cartridge 46, and when it arrives at tape lead-out aperture 64 thefree end of the tape is pulled out through that aperture by theoutwardly flowing air current.

As a result of the air flows from high-pressure air ejection outlets 34and 36, disposed on the left and right sides of base 20 as shown in FIG.1, (with the main effects being produced by air ejection outlet 34), thefree end of the tape which emerges from tape lead-out aperture 64 istransported and guided to portion 18b of the tape transport parth 18. Asa result of the air flow from high-pressure air ejection outlet 38,provided to the left of the central region of base 20, the direction ofadvancement of the free end of the tape is directed in a curved path,following the direction of the center of tape transport path 18, asillustrated in FIG. 1. Due to the combined actions of the air flows fromhigh-pressure air ejection outlets 34 and 38, the free end of the tapeis thereby guided past tape start/end detection section 24.

Embodiments of tape start/end detection section 24 will now bedescribed, referring first to FIGS. 5 to 8.

FIG. 5 is a partial expanded plan view of the embodiment of FIG. 1,illustrating the portions of the unit adjacent to tape start/enddetection section 24. The shape of the tape start/end detection section,as seen in vertical cross-section, is shown in FIG. 6, and this ispositioned in the tape transport path as shown in FIG. 5. Numeral 70denotes a member having a rectangular cross-sectional shape, open at oneside as shown in FIG. 6. The closed side of member 70 is positioned onthe opposite side of the tape transport path from the magneticread-write head section, while the open side of member 70 is disposedjust before the head section. The size of gap H between the top andbottom portions of member 70 is made greater than the width of the tape,by a suitable margin, to ensure that the tape can run freely throughtape start/end detection section 24. The upper surface 70a of the lowerpart of member 70 is arranged to be co-planar with the lower surface ofthe tape transport path, so that no obstruction will be presented to thetape by member 70.

Numeral 72 denotes a photo-emissive element such as a light-emittingdiode, which is mounted obliquely in an aperture 74 in the upper part ofmember 70, and which projects light towards tape 22 as shown in FIG. 6.Numeral 76 denotes a photo-receptive element which is mounted obliquelyin an aperture 78 in the lower part of member 70. The photo-emissiveelement 72 and photo-receptive element 76 are each mounted such as notto protrude out of member 70 into the tape transport path, so that noobstruction to the movement of the tape is presented by these at anytime. Numeral 80 denotes a tape start or tape end mark formed on tape22, which has a substantially higher degree of reflectance than the tapeitselt. Light emitted from photo-emissive element 72 falls on this markand is reflected therefrom as shown, to impinge upon photo-receptiveelement 76. An electrical signal, i.e, a detection signal, is therebyproduced by photo-receptive element 76 and this is sent to a controlsection (described hereinafter) to indicate that the end of the tape orthe start of the tape has moved past tape start/end detection section24.

With such a configuration for tape start/end detection section 24, thetape transport path is left wide and completely unobstructed, to therebyfacilitate automatic tape threading from the tape supply section to thetape take-up section. This is in contrast with conventional types oftape start/end detection means, which generally obstruct or narrow thetape transport path to a substantial degree.

FIG. 7 and FIG. 8 show another embodiment of a tape start/end detectionselection according to the present invention. In this case the tapestart/end detection section, denoted by numeral 25, again comprises ambmer 82 having a rectangular cross-sectional shape, open at one side,and is mounted with the open end thereof positioned in the tapetransport path and the closed end disposed on the same side of the tapetransport path as the magnetic read-write head. The operation of thisembodiment is identical to that of the embodiment of FIGS. 5 and 6described above. As in the previous embodiment, the upper face 82a ofthe lower part of member 82 of tape start/end detection section 25 ismade co-planar with adjacent areas of the tape transport path, and thephotoemissive element 72 and photo-receptive element 76 do not protrudeoutwards from member 82 into the tape transport path, so that noobstruction is presented to the movement of the tape during automaticthreading or normal read-write operation of the unit.

After passing through tape start/end detection mechanism section 24, thefree end of the tape moves past a cleaner 28 and magnetic read/writehead 26, and is then guided onto the periphery of take-up hub 49 by theaction of winding securing mechanism 48. Specifically, the high pressureair flow from air ejection outlet 38 passes along vertical wall portion86 of the tape transport path, and then is directed towards take-up hub49 by shape and position of winding securing mechanism 48. The air flowthus directed, designated as W in FIG. 1, acts to lead the free end ofthe tape onto the peripheral face of takeup hub 49.

An encoder 88 is provided in tape take-up section 16, and signalsproduced by this are utilized to hold the speed of movement of the tapeat a constant value, when the magnetic tape drive unit is in normal reador write operation. Encoder 88 moves about a shaft 90 as a center ofrotation, and floats on the tape which is wound on take-up hub 49. Ashield plate 92 is provided on encoder 88, and the provision of thisshield plate, in conjunction with the particular shape of a portion 147of the vertical side wall of the tape transport path, serve to ensurethat the free end of the tape will not accidentially enter the tapetake-up section 16 on the wrong side of take-up hub 49 (i.e. such as tomove around hub 49 in a counter-clockwise direction rather than in aclockwise direction, as viewed in FIG. 1).

FIG. 9 is a partial cross-sectional view of the tape take-up section 16.This comprises a drive motor 94, with the drive shaft thereof havingtake-up hub 49 fixedly mounted thereon, a tape dropping prevention plate96, and a fixed pin 98 which is fixedly attached to take-up hub 49 torotate therewith. A shield member 100 is disposed between drive motor 94and tape dropping prevention plate 96, with a suction aperture 102 beingformed in shield member 100 through which air flows in the direction ofthe arrow. This air flows through a pipe (not shown in drawings). to aninlet port of blower section 40 shown in FIG. 1, which produces thesupply of high pressure air that is ejected from air ejection outlets 32to 38 as described above, so that suction is applied at aperture 102. Aflat vertical face 48b is provided on an elongated member 48c of windingsecuring mechanism 48, which redirects the air flowing from apertures 38etc, towards the periphery of hub 49. This redirected air flow acts toguide the tape free end onto the hub periphery. Elongated member 48c isrotatably mounted on base 12 at one end, and springlocated such as tourge a roller 48a mounted on the opposite end of member 48c, against theperiphery of hub 49. As a result, the tape free end, after being guidedonto the hub periphery by the redirected air flow, becomes pressed intocontact with that peripheral surface and so moved by the rotating hub topass between the hub surface and roller 48a. In this way, the tapebecomes securely wound onto hub 49. After the tape has started to windonto the hub, the pressure applied by roller 48a on the tape surfaceacts to ensure envenness of winding of the tape.

As described previously, the free end of the tape is forced onto theperipheral surface of take-up hub 49 by a suitably directed air current.The flow of air through the lower part of take-up hub 49 assists inpulling the free end of the tape onto the hub periphery, therebyassisting in ensuring that the tape is securely woound onto take-up hub49, in conjunction with the winding securing mechanism 48.

After the tape has been wound onto the take-up hub 49 by the automaticwinding securing operations described above, it is necessary to confirmthat the tape has been correctly and securely attached to the take-uphub. With this embodiment of the present invention, such confirmation isprovided by means which generate signals indicating that the tape is incontact with the external faces of magnetic read/write head 26 andcleaner 28, and means which indicate that a mini-tension arm (describedin the following) is held in a specific position.

FIG. 10 is an oblique view of the mini-tension arm mechanism. Themini-tension arm 104 is supported on a convex base portion 54, rotatablymounted on a shaft 110. As shown, the mini-tension arm 104 is providedwith a first contact arm 108 and a second contact arm 106 which aredisposed substantially mutually at right angles. As described in thefollowing, the lower end of second contact arm 106 is positioned higherthan the upper end face of a guid roller 112. The mini-tension arm 104is provided with a spring 114, which serves to determine a stableposition for mini-tension arm 104. The possible stable states ofmini-tension arm 104 are described in detail hereinafter. Guide roller112, which also acts as a stopper for first contact arm 108, isrotatably mounted in base portion 54, and serves to guide the tape. Anaperture 116 is formed in base portion 54 adjacent to mini-tension arm104, and an actuator 119 of a micro-switch (not shown in the drawings)disposed beneath base portion 54, protrudes through aperture 116. Thus,as mini-tension arm 104 moves about shaft 110 as a center of rotation,the lower face 104a of mini-tension arm 104 presses against actuator119, and operates the micro-switch.

The operation of mini-tension arm 104 will be described furtherreferring to FIGS. 11 to 13. Fig. 11 shows the positions of themini-tension arm and the tension arm 47, before the tape is wound ontothe take-up hub 49. FIG. 12 shows the positions of minitension arm 104when the tape has been correctly wound on the take-up hub and tension isbeing applied to the tape. FIG. 13 shows the position of mini-tensionarm 104 while the magnetic tape drive unit is in operation.

In FIGS. 11 to 13, numeral 120 denotes a guide roller which is rotatablymounted on the outer end of tension arm 47, and which impinges againstthe first contact arm 108 and second contact arm 106 of minitension arm104. This guide roller 120 is used to change the stable state positionsof mini-tension arm 104. Numeral 122 denotes the path along which guideroller 120 moves. As shown in FIG. 11, prior to tape 22 being wound onthe take-up hub, then due to the action of spring 114 acting about theaxis of shaft 110, the first contact arm 108 is held in a stableposition in contact with guide roller 112. This condition will bedesignated as position A of tension arm 47. Positions B and X alongmovement path 122 of guide roller 120 indicate the range of movement oftension arm 47, that is, the maximum and minimum positions of guideroller 120.

When the free end of the tape from reel 42 in tape supply section 14 ispulled outward and is automatically wound onto take-up hub 49 of tapetakeup section 16 as described above, the speed of rotation of take-uphub 49 is made higher than that of reel 42. Thus, as shown in FIG. 12,tension is thereby applied to tape 22 when it has become wound onto hub49. As a result, the first contact arm 108 of mini-tension arm 104 isset in contact with tape 22, and due to the tension applied to tape 22the mini-tension arm is moved to the position shown in FIG. 12, i.e. isrotated. Hence, as shown in FIG. 10, actuator 119 of the micro-switchdescribed hereinabove with reference to FIG. 10 is depressed, and themicroswitch is thereby actuated. With mini-tension arm 104 in theposition shown in FIG. 12, since spring 114 is pulling such as to rotatemini-tension arm 104 in the clockwise direction (as seen from above)about shaft 110, the tension in tape 22 is reduced. As a result,mini-tension arm 104 is returned to the stable state position shown inFIG. 11. However, in response to the actuation of the micro-switch and asignal produced thereby, tension arm 47 is made to move along path 122to position B shown in FIG. 12. When this occurs, guide roller 120 ontension arm 47 strikes against contact arm 108 of tension arm 104,acting through tape 22, and mini-tension arm 104 is thereby moved in thecounter-clockwise direction, accompanying the motion of tension arm 47.As a result, spring 114 is now positioned on the left hand side of shaft110, so that the tension force exerted by spring 114 acts to pull onmini-tension arm 104, whereby mini-tension arm 104 rotates about shaft110 until it is halted by stopper (not shown in the drawings), tofinally reach the stable state position shown in FIG. 13.

With mini-tension arm 104 in the stable state position shown in FIG. 13,the length of contact arm 108 is predetermined such that the tip ofcontact arm 108 does not touch guide roller 120 as the latter moves intoposition X.

While the magnetic tape drive unit is performing read or writeoperations, tension arm 47 floats in the region between positions B andX. The guide roller 120 only reaches position X, and as stated abovedoes not touch the second contact arm 106. Thus, while the unit is inoperation, tension arm 104 is held in the stable state position shown inFIG. 13.

When operation of the magnetic tape drive unit is terminated, tensionarm 47 is moved along path 122 to return to position A. When thisoccurs, guide roller 120 strikes the tip of second contact arm 106 ofminitension arm 104, whereby mini-tension arm 104 moves to the right,rotating about shaft 110. Thus when spring 114 becomes positioned on theright hand side of shaft 110, the tensile force exerted by the springacts to return mini-tension arm 104 to the stable position shown in FIG.11. In this way, mini-tension arm 104 implements recovery to the initialstable position. As stated above, due to the tension which is applied totape 22 when the tape is correctly wound onto the take-up hub, resultingfrom the differences between the speeds of rotation of the tape reel(i.e. of retainer 103) and the speed of rotation of the take-up hub,mini-tension arm 104 acts on actuator 119 such as to operate themicro-switch. In this way, a tape attachment confirmation signal isproduced by the micro-switch. If this signal is not generated withinpredetermined time after automatic tape threading and attachmentoperations are initiated, then tape 22 is rewound onto reel 42 andautomatic tape attachment operations are restarted.

In the above embodiment, a micro-switch and actuator are used to sensethe tension arm position and produce sensing signals accordingly.However various other methods could be used to produce such tapeattachment confirmation signals. For example, light from aphoto-emissive diode could be directed onto the lower face 104a ofmini-tension arm 104, and light reflected therefrom detected by aphotoreceptive diode.

FIG. 14 is a simplified block diagram to illustrate the generalconfiguration of circuit means for controlling a magnetic tape driveunit according to the present invention. Numeral 124 denotes a tapecontrol section 124 which is connected to a tape supply section driveunit 126, to a tape take-up section drive unit 128, to a tape passsensor 130, to a blower unit 132, to a BOT/EOT sensing section 134, to atension arm mechanism 136 and to a reel clamping mechanism 138.

The tape control section 124 receives control signals or sensor signalsfrom sensors or other signal generating devices, performs specificprocessing of these received signals, and in response transmits controlsignals to the various sections of the magnetic tape drive unit tothereby control automatic tape attachment, operation following automatictape attachment, rewinding of the tape, etc. The tape supply sectiondrive unit 126 basically corresponds to drive motor 126, while tapetake-up section drive unit 128 basically corresponds to drive motor 94.These drive motors are controlled for forward and reverse rotation andfor speed of rotation by control signals sent from tape control section124.

The tape pass sensor 130 comprises means for sensing that the free endof the tape has passed by, and is provided at some intermediate positionalong tape transport path 18. In the case of the embodiment of FIG. 1,this is provided in the vicinity of tension arm 47, and comprises aphoto-emissive diode 140 and a photoreceptive diode 142.

The blower unit 132 serves to supply air under pressure to thehigh-pressure air ejection outlets 34, 30, etc, and has an air suctioninlet which is coupled to suction aperture 102 of take-up section 16.The blower unit 132 is controlled by control signals from tape controlsection 124 such as to produce air flows whereby the free end of thetape is correctly transported to the take-up hub and wound thereon atthe time of automatic tape attachment operation.

The BOT/EOT sensing section 134 corresponds to tape end/start sensorsection 24 described in the above, and acts to sense the marks providedon the tape indicating the start (BOT) and end (EOT) of the tape,producing in response corresponding detection signals which are sent totape control section 124.

The tension arm mechanism 136 provides a predetermined amount of tensionon tape 22 in response to control signals from tape control section 124,and also serves to produce tape attachment confirmation signals toindicate when the tape has become correctly attached to the take-up hub,immediately following automatic tape attachment. These signals are sentto tape control section 124. In the previous embodiment, tension armmechanism 136 is made up of tension arm 47, mini-tension arm 104, etc,described above.

The reel clamping mechanism 138 receives control signals from tapecontrol section 124, and acts to clamp reel 42 in a concentrically fixedrelationship with the drive motor shaft, as described in detailhereinafter, after the reel has been inserted into the magnetic tapedrive unit.

Referring now to FIG. 15, another embodiment of a magnetic tape driveunit according to the present invention is shown in plan view. This isessentially similar to the embodiment of FIG. 1, but is of openreeldesign, i.e. the tape reel 42 is not contained within a cartridge as inthe case of the previous embodiment. The automatic tape attachmentoperation for this embodiment is as follows. First, reel 42 is rotatedin the clockwise direction, as viewed in FIG. 15, while a high-pressureair flow is produced from outlets 30 and 32 (which can be positioned ina similar manner to that described above for the first embodiment), andfrom high-pressure air ejection outlets 34 and 38. the high-pressure airflow from outlet 32 impinges upon the surface of tape 14, wound on reel42, and acts to separate the free end of the tape from adjacent portionsof tape. The high-pressure air flow from air ejection outlet 34, andthen that from air ejection outlet 36, then act to guide and transportthe free end of the tape along the tape transport path, first movingpast wall portion 146 towards tension arm mechanism 20, which at thistime is in the retracted state. The subsequent operation is similar tothat described above for the embodiment of FIG. 1, and so furtherdescription will be omitted.s

FIG. 16 shows a plan view of another embodiment of an open-reel type ofmagnetic tape drive unit according to the present invention. Thisdiffers from the embodiments described above in the shape of the tapesupply section 14 and in the tension application mechanism 20. Numerals148, 150 152 and 154 denote high pressure air ejection outlets whichproduce air flows for separating the free end of the tape from adjacenttape 44 wound on reel 42 in the tape supply section and transporting thefree end of the tape to the tape take-up section 16, as in the previousembodiment.

In this embodiment, the portion of base 141 containing tape supplysection 14 is formed with a broad concave shape, as shown. The highpressure air ejection outlets 148, 150 and 152 are formed in the outerwall of the portion of base 141 containing tape supply section 14, andact to free the outer end of the tape 44 from the reel, and transportthis free end of the tape along tape transport path 18. It can thus beunderstood that the operation of this embodiment is essentially similarto those described hereinabove.

The mechanism for clamping the reel 42 on shaft 51 of drive motor 50will now be described, referring to FIGS. 17 to 3. FIG. 17 is a verticalcross-sectional view of tape supply section 14 before automatic clampingof the reel is performed. FIG. 18 is a plan view of the reel clampingmechanism. FIG. 19 is a cross-sectional view of the embodiment of FIG.18, taken in the direction of arrows 4--4, and FIG. 20 is a plan view ofa portion of the embodiment of FIG. 17, taken in the direction of arrows5--5 in FIG. 17. In FIGS. 17 to 10, the shaft 51 of drive motor 50 isfixedly attached to a rotary disc 158 by bolt 160, to thereby rotatewith shaft 51. A position determining block 162 is fixedly attached tothe top face of rotary disc 158 by screws 164, while an eccentric disccam 166 is rotatably mounted by a screw 168, on the opposite side ofshaft 51 from position determining block 162. In this way, an upper disc172 is supported for horizontal sliding motion with respect to rotarydisc 158. That is to say, position determining block 162 is fixedlyattached to rotary disc 158 by screws 164, and supports the lower faceof upper disc 172, while washers 174 positioned over elongated apertues176 formed in upper disc 172 bear against the upper face of upper disc172. The eccentric disc cam 166 is rotatably coupled to rotary disc 158by screw 168, passing through elongated aperture 180 formed in upperdisc 172, so that eccentric disc cam 166 also supports the lower face ofupper disc 172. Numeral 182 denotes an annular rubber belt which passesaround position determining block 162 and eccentric disc cam 166 asshown in FIG. 18.

The position determining block 162 is fixed in a position such that thedistance from the center of shaft 152 to the outer face of annularrubber belt 182 is identical to the radius of the mounting aperture inreel 42. In this way, the radius of curvature of the outer face ofannular rubber belt 182 is made identical to the radius of that mountingaperture.

A guide pin roller 184 is provided on the lower face of eccentric disccam 166, having a shaft which passes through an elongated aperture 186formed in rotary disc 158. As stated above, the upper disc 172 ismounted for sliding movement in the horizontal direction with respect torotary disc 158, and in addition two pillars 188 are fixed by screws 190in upper disc 172. The lower end of each of pillars 188 slides freelyover the upper face of rotary disc 158. The annular rubber belt 182passes over and in contact with these pillars 188, around positiondetermining block 162, and around eccentric disc cam 166.

As shown in FIG. 20, a cam 192 having the contour shown is rotatablymounted on shaft 152 of drive motor. A groove 192a is formed around theperiphery of cam 192, while a protrusion 192b is formed within groove192a as shown in FIG. 17. Numerals 192 denotes a solenoid equipped withan operating rod 196. Normally, rod 196 is held in a retracted conditionas shown in FIG. 17, by the action of a spring 198. However whenclamping of reel 42 is to be initiated, solenoid 194 is energized whilemotor shaft 152 is rotated at a relatively slow speed, whereby rod 196is pushed outward to engage within groove 192a. When protrusion 192bengages rod 196, then rotation of cam 192 is halted. Then, as a resultof the rotation of rotary disc 158 (which is rotating as a unit withshaft 152 of drive motor), guide pin roller 184 of cam 192 follows theouter contour of cam 192, whereby eccentric disc cam 166 moves with afloating motion about screw 168 as a center of rotation. As a result ofthis rotation of eccentric disc cam 166, it is moved peripherallyoutward, and thereby presses annular rubber belt 182 into contact withthe left hand side (as viewed in FIG. 17) of the side wall of themounting aperture in reel 42. As eccentric disc cam 166 moves farther inthe peripherally outward direction, reel 42 is moved in the directionindicated by arrow Z in FIG. 17, whereby the right hand side of of theinner periphery of the central aperture in reel 42 (indicated as R inFIG. 17) becomes pressed against the peripheral surface of upper disc172, acting through annular rubber belt 182 positioned between them.When this occurs, movement of upper disc 172 and reel 42 in thedirection Z is halted.

At this time, 2-point contact is established between the inner peripheryof the mounting aperture in reel 42 and position determining block 162and eccentric disc cam 166, acting through annular rubber belt 182,which serves to clamp reel 42 accurately in a central position,concentric with shaft 152 of drive motor 151.

Furthermore, when eccentric disc cam 166 moves in a peripherally inwarddirection, i.e. is pulled inward, then as a result of the tensile forceproduced by annular rubber belt 182, forces are applied to pillars 188which act in the opposite direction to direction Z, i.e. which acttoward the right as seen in the diagrams. As a result, upper disc 172 isreturned to its original position. In this way, upper disc 172 slideshorizontally with respect to rotary disc 158.

The shape of the periphery of annular rubber belt 182 before reelclamping is performed is shown in FIGS. 17 to 19. In all of thepositions shown, annular rubber belt 182 is disposed within theperiphery of upper disc 172, to thereby facilitate setting reel 42 onrotary disc 158. That is to say, the inner diameter of the mountingaperture in reel 42 is slightly larger than the diameter of upper disc172. Thus as described above, when eccentric disc cam 166 is rotated,then when a condition is reached in which reel 42 is clamped in place,the portion of annular rubber belt 182 which passes over the arc-shapedportion of the periphery of position determining block 162 attainssubstantially the same contour as the periphery of upper disc 172. Inaddition, the external face of annular rubber belt 182, passes aroundeccentric disc cam 166, projects slightly beyond the periphery of upperdisc 172, while the distance from the upper face of rotary disc 158 tothe lower face of upper disc 172 is made slightly less than the width ofreel 42.

The operation of the above reel clamping mechanism can be summarized asfollows. When reel 42 is to be clamped in place, it is first set onrotary disc 158. The solenoid 194 is then energized, whereby rod 196 ispushed into groove 198 in cam 192. Drive motor 151 is then energizedsuch as to rotate shaft 152 relatively slowly in the direction indicatedby arrow 30, with rotary disc 158 and cam 192 being thereby rotated inthe same direction. Within one half-revolution of motor shaft 152, rod196 catches on the protrusion 17b in groove 192a, whereby cam 192 isrestrained against further rotation. However, rotary disc 158 continuesto rotate, so that differential rotation occurs between rotary disc 158and cam 192. That is to say, rotary disc 158 rotates with respect to cam192 in the direction shown by the arrows in FIG. 20. At this time, guidepin roller 184 of eccentric disc cam 166 follows the profile portion F-Gof cam 192, so that eccentric disc cam 166 moves in a peripherallyoutward direction, rotating about screw 168. As a result of this outwardmotion of eccentric disc cam 166, it becomes pressed against the leftside L of the mounting aperture in reel 42, acting through annularrubber belt 182. As eccentric disc cam 166 continues to be movedperipherally outward, it pushes 42 in the direction indicated by arrow Zin FIG. 17. Finally, side portion R of the inner wall of the mountingaperture in reel 42 is pressed against position determining block 162,acting through annular rubber belt 182. Reel 42 is now firmly clamped torotary disc 158. The solenoid 194 is then deenergized, whereby rod 196is retracted.

The clamped status described above, at the point when clamping has beencompleted but solenoid rod 196 has not yet been retracted, is shown inthe plan view of FIG. 21 and the vertical cross-sectional view of FIG.22, taken in the direction of arrows 6--6. FIG. 23 shows the position ofcam 192 at this time.

The manner in which reel 42 is unclamped is as follows. First, solenoid194 is actuated, to thereby extend rod 196 into groove 192a in cam 192.The drive motor shaft 152 is then rotated relatively slowly in theopposite direction to that indicated by the arrow in FIG. 20. Within onehalf-revolution of shaft 152, rod 196 engages against protrusion 192b ingroove 192a, so that rotation of cam 192 is halted. However rotary disc158 continues to rotate, whereby differential rotation occurs betweenrotary disc 158 and cam 192. As a result, guide pin roller 184 followsthe contour portion G-F of cam 192, so that the portion of annularrubber belt 182 which passes around pillars 188 exerts a tensile forceacting such as to pull pillars 188 in the direction opposite to thatshown by arrow Z in FIG. 17, whereby upper disc 172 and reel 158 aremoved in the opposite direction to that of arrow Z. In this way, reel 42is released from attachment to rotary disc 158.

As shown in the drawings, the portions of the external face of annularrubber belt 182 which pass around position determining block 162 andeccentric disc cam 166 come within the periphery of upper disc 172, andthereby become displaced from the inner aperture in reel 42. Thecondition prior to clamping the reel has now been restored. The solenoid194 is then re-energized, so that rod 196 is retracted. Reel 42 can nowbe removed from upper dics 172.

With an automatic reel clamping mechanism having the configurationdescribed above, reel 42 is clamped to rotary disc 158 at two supportpoints. One of these support points is fixed in place, and so can bedetermined to a high degree of precision, while the other support pointis movable. As a result of this arrangement, reel 42 is clamped inposition with a high degree of accuracy, and in addition thisarrangement ensures that reel 42 will be held in a precisely concentricrelationship with the drive motor shaft 152. Use of two support pointsin this way also has the advantage of simplifying the overall mechanicalconfiguration of the automatic reel clamping mechanism.

FIG. 24 is a cross-sectional view through the tension applicationmechanism of the embodiment of FIG. 16, taken in the direction of arrows6--6. The top of a shaft 200 is fixedly attached in an aperture in oneend of tension arm 202, while the other end of tension arm 202 supportsa roller 204 which is rotatably mounted thereon by a pin 206. Roller 204serves to guide tape 22. Shaft 200 is rotatably mounted on base 25 bybearings 208 and 210. A connecting member 212 is mounted on the lowerend of shaft 200, and serves to coupled shaft 200 to the shaft of apotentiometer 219. The connecting member 212 is fixedly attached toshaft 200 and the shaft of potentiometer 219 by mounting screws 216 and218.

A rotation angle detection lever 220 is fixed to connecting member 212by a screw 222. A micro-switch 224 is positioned such that an actuator226 thereof attached to the underside of base portion 228 is arranged tobe depressable by one end of rotation angle detection lever 220. Whentension arm 202 is displaced due to some reason as the tension in tape22, then shaft 200 is rotated accordingly, and rotation angle detectionlever 220 coupled thereto is also rotated. When the amount of angularrotation is tension arm 202 exceeds a predetermined amount, thenrotation angle detection lever 220 depresses actuator 226 ofmicro-switch 224, to thereby actuate microswitch 224.

FIG. 25 is a partial plan view for describing the arrangement of partsin the vicinity of tension arm 202 and the rotation angle detectionmeans of FIG. 24. FIG. 26 is a cross-sectional view taken in thedirection of arrows 7--7 in FIG. 25, showing means for driving a latchpin. In FIGS. 25 and 26, a solenoid 230 is fixedly attached to theunderside of base portion 166, by a solenoid attachment plate 232. Aslot is formed in the outer end of operating rod 234 of solenoid 230,and a latch lever 236 having a rectangular shape open at one side, asviewed in cross-section, is engaged in this slot by means of a screw238. One end of latch lever 236 is rotatably supported on base 166 by ashaft 240, while the other end of lever 236 is fixedly attached to shaft242 of latch pin 248. Shaft 224 protrudes through an aperture 244 whichis formed in base portion 228, and pawl portion 202a of tension arm 202is disposed such as to contact roller 246 on the other end of shaft 242.

With this configuration, when the drive means coupled to latch pin 248are activated, that is when solenoid 230 is energized, then operatingrod 234 of solenoid 230 is drawn into the solenoid, whereby latch pin248 moves towards solenoid 230, rotating about shaft 240. Thus, latchpin 248 moves from right to left, as indicated by the arrow in FIG. 25,i.e. moves from the front towards the rear, as viewed in FIG. 24 As aresult, pawl portion 202a of tension arm 202 becomes disengated fromlatch pin 248, thereby freeing tension arm 202. Thus, tension arm 202 ispulled into the position shown by the broken-line outline in FIG. 16, bythe tension force exerted by spring 249.

FIGS. 27a to 27d are diagrams for describing the engaging relationshipsbetween the latch pin 248 are the pawl portion 202a of tension arm 202,and show tension arm 202 moves from the position shown by thebroken-line outline in FIG. 16 into position K, by the interactionbetween pawl portion 202a of tension arm 202 and latch pin 248 i.e. showhow tension arm 202 is moved to the left, as viewed in FIG. 22. When themagnetic tape drive unit is operating in the normal read or write mode,then pawl portion 202a of tension arm 202 is disposed in a positionwhich is separated from latch pin 248, as shown in FIG. 27a, i.e.position M. When the tension arm 202 is moved to the left from positionM, then as shown in FIGS. 27c, pawl portion 202a (or more specificallythe linear contour portion 202b of pawl portion 202a) acts to rotateroller 246 of latch pin 248, while in addition pawl portion 202a presseslatch pin 248 towards the left. As this is taking place, althoughsolenoid 230 is in the de-energized state, operating rod 234 is movedtowards solenoid 230 and spring 235 is compressed. As tension arm 202moves further to the left, roller 246 of latch pin 248 becomes separatedfrom the linear portion 202 of pawl portion 202a of tension arm 202, sothat due to the force exerted by compressed spring 235, latch pin 248 ismoved to the right. As a result, as shown in FIG. 27d, tension arm 202becomes latched in the position shown.

The operation whereby tension arm 202 is retracted will now bedescribed. It will be assumed that the tape is to be rewound fromtake-up hub 49 onto reel 42 in tape supply section 14. This is performedby rotating reel 42 in the counterclockwise direction. While this istaking place, tension arm 202 is held in position M (indicated by thebroken-line outline) in the same way as during read or write operations,so that pawl portion 202a of tension arm 202 is in the position shown inFIG. 27a. When rewinding of the tape is almost completed, then the tapeend/start detection section 24 senses the BOT mark on tape 22, andproduces a detection signal. In response to this, tape drive section 900sends a signal to tape take-up section 16 designating that rotation oftake-up hub 49 be halted or the hub set into reverse rotation. When thistakes place, tension is applied to tape 22, and so to the portionthereof which is guided onto roller 204 on the end of tension arm 202.As a result of this tension, tension arm 202 moves towards position K,and shaft 200 moves in accompaniment to this movement of tension arm202. This rotation of shaft 200 serves to rotate rotation angledetection lever 220 about the axis of shaft 200. As the tension appliedto tape 22 acting on roller 204 increases, tension arm 202 moves toposition K (shown by the full-line outline), so that pawl portion 202aengages with latch pin 248, as illustrated in FIG. 27d, i.e. in alatching relationship. As the tension applied to tape 22 increasesfurther, so that tension arm 202 moves from position K further towardsthe left, the rotation angle detection lever 220 depresses actuator 226of micro-switch 224, thereby actuating micro-switch 224. Themicro-switch 224 is positioned such as to be actuated when tension arm202 is displaced by an angle of more than a predetermined value. Tapecontrol unit 900 responds to the actuation of micro-switch 224 byproducing control signals which set take-up hub 49 in a condition inwhich it can freely rotate. The tension of tape 22 is thereby reduced,whereby the tape can be completely rewound onto reel 42. While thistakes place, tension arm 202 is latched in position K, i.e. in theretracted condition, so that the tape transport path 18 is wide andclear. In this way, the free end of the tape can easily move along tapetransport path 18 past tension application mechanism 20 when the nextautomatic tape attachment operation is carried out.

The micro-switch 224 also serves to produce a tape attachmentconfirmation signal when automatic tape attachment onto take-up hub 49is implemented, to indicate that the tape has been corrently wound ontothe hub. That is to say, as in the embodiment of FIG. 1, the speed ofrotation of take-up hub 49 is made higher than that of reel 42 whileautomatic tape attachment is in progress, so that tension is applied tothe tape. As a result of this tension, tension arm 202 is moved fromposition K towards the left, and micro-switch 224 is thereby actuated.This actuation produces an attachment confirmation signal. If such anactuation does not occur within a predetermined time, then tape 22 isrewound on reel 42, and automatic tape attachment operation isre-executed, in the same way as for the embodiment of FIG. 1.

After performing automatic tape attachment, i.e. with the tape correctlyattached to the take-up hub, then a control signal is sent to solenoid230 acting to energize solenoid 230. As a result, operating rod 234moves ratchet lever 236 towards solenoid 230, whereby latch pin 248becomes disengaged from pawl portion 202a of tension arm 202. Thus,tension arm 202 is pulled by the force exerted by spring 249 intoposition M (shown by the broken-line outline in FIG. 16), therebyapplying a predetermined amount of tension to the tape.

It should be noted that although in the above description, rotationangle detection lever 220 actuating micro-switch 224 constitutesrotation angle detection means, it is equally possible to use variousother means for this. For example, such sensing can be carried out byusing potentiometer 219 mounted on the lower end of shaft 200.Furthermore, various other means can be envisaged for moving latch pin248, besides solenoid 230.

Although the present invention has been described in the above withreference to a specific embodiment, it should be noted that variouschanges and modifications to the embodiment may be envisaged, which fallwithin the scope claimed for the invention as set out in the appendedclaims. The above specification should therefore be interpreted in adescriptive and not in a limiting sense.

We claim:
 1. An automatic-threading horizontal type of magnetic tapedrive unit, comprising:a housing with the interior thereof horizontallydisposed; a base horizontally disposed within said housing; a tapesupply section disposed on said base, comprising means for retaining androtating about a substantially vertical axis a tape reel having a coilof magnetic tape wound thereon terminating in a free end; a tape take-upsection disposed on said base, comprising a take-up hub and means forsupporting and rotating said take-up hub about a substantially verticalaxis; an S-shaped tape transport path means formed as an open channel insaid base and extending between said tape supply section and said tapetake-up section, said tape transport path means defining a tapetransport path for said magnetic tape; magnetic head means disposed at aposition along said tape transport path between said tape supply sectionand said tape take-up section, for performing read and write operationson said magnetic tape; a source of air under high pressure; a pluralityof high-pressure air outlets for producing high pressure air flows,supplied with air from said high-pressure air source, and disposedvariously adjacent to the periphery of said tape reel and at positionsalong said tape transport path, for directing said high-pressure airflows such as to separate said tape free end from adjacent portions ofsaid magnetic tape wound on said tape reel and to guide and transportsaid tape free end after said separation, along a substantially centralregion of said tape transport path to said tape take-up section; windingsecuring means disposed in said tape take-up section, acting to windsaid magnetic tape onto said takeup hub after said tape free end hasbeen transported to said tape take-up section by said high-pressure airflows; a main tension arm operable to be moved between a first positionin which said main tension arm is disposed substantially outside saidtape transpoft path and a second position in which said main tension armextends into said tape transport path such that said main tension armbears against said magnetic tape and deflects said magnetic tape fromsaid tape transport path to thereby produce a predetermined amount oftension; an auxiliary tension arm rotatable about a substantiallyvertical axis between a first and a second stable position, spring meansbiasing said auxiliary tension arm in said first and second stablepositions, said auxiliary tension arm being in said first stableposition prior to winding said magnetic tape onto said take-up hub, saidtape being subjected to tension immediately after said tape is woundonto said take-up hub such that a portion of tape which has just beentensioned bears against said auxiliary tension arm and thereby rotatessaid auxiliary tension arm from said first stable position to anintermediate position, said intermediate position being between saidfirst and second stable positions; switch means actuated by saidauxiliary tension arm when said auxiliary tension arm is rotated fromsaid first position to said intermediate position, said actuated switchmeans generating a signal to move said main tension arm from said firstto said second position thereof; said auxiliary tensionarm beingdisposed within the path of movement of said main tension arm such thatsaid main tension arm contacts a portion of said auxiliary tension armwhere said main tension arm moves from said first position toward saidsecond position, said main tension arm in moving from said first towardssaid second position thereby shifting said auxiliary tension arm fromsaid intermediate position to said second stable position.
 2. Anautomatic-threading horizontal type of magnetic tape drive unitaccording to claim 1 wherein said spring means is connected to saidauxiliary tension arm to bias said auxiliary tension arm in onerotational direction when said auxiliary tension arm is in said firststable position and to bias said auxiliary tension arm in an oppositerotational direction when said auxiliary tension arm is in said secondstable position.
 3. An automatic-threading horizontal type of magnetictape drive unit according to claim 2 wherein said spring means biasessaid auxiliary tension arm in said one direction when said auxiliarytension arm is in said intermediate position.
 4. An automatic-threadinghorizontal type of magnetic tape drive unit according to claim 1 whereinsaid spring means is connected to said auxiliary tension arm such thatsaid spring means extends on one side of said axis of rotation of saidauxiliary tension arm when said auxiliary tension arm is in said firststable position and said spring means extends on an opposite side ofsaid axis of rotation of said auxiliary tension arm when said auxiliarytension arm is in said second stable position.
 5. An automatic-threadinghorizontal type of magnetic tape drive unit according to claim 1 whereinsaid auxiliary tension arm comprises a first contact arm and a secondcontact arm, said magnetic tape contacting said first contact arm tomove said auxiliary tension arm from said first stable position to saidintermediate position, said main tension arm contacting said secondcontact arm to move said auxiliary tension arm from said second stableposition to said first stable position.
 6. An automatic-threadinghorizontal type of magnetic tape drive unit according to claim 5 whereinsaid second contact arm is connected to said first contact arm andextends from said first contact arm at an angle other than a straightangle.
 7. An automatic-threading horizontal type of magnetic tape driveunit according to claim 6 wherein said first contact arm is disposed inthe path of movement of said main tension arm when said auxiliarytension arm is in said intermediate position, said main tension armbeing rotatable from said first position to said second position tocontact said first contact arm to thereby rotate said auxiliary tensionarm from said intermediate position to said second stable position. 8.An automatic-threading horizontal type of magnetic tape drive unitaccording to claim 1 wherein said switch means comprises aswitch-actuating part movable between a non-actuating position and anactuating position, said switch-actuating part being in saidnon-actuating position when said auxiliary switch means is in said firststable position, said switch-actuating part being in said switchactuating position when said auxiliary tension arm is in saidintermediate position.
 9. An automatic-threading horizontal type ofmagnetic tape drive unit according to claim 8 wherein said main tensionarm is disposed on one side of said tape as said tape moves along saidtransport path and said auxiliary tension arm is disposed on an oppositeside of said tape as said tape moves along said transport path.